package com.gthncz;

import java.util.*;
import java.util.concurrent.ConcurrentHashMap;

public class CollectionDemo {


    public static void main(String[] args) {
        Object obj = new Object();

        Set<Integer> set = new HashSet<>();
        Map<Integer, Object> map = new HashMap<>();

        ArrayList<Integer> arr = new ArrayList<>();
        LinkedList<Integer> linkedList = new LinkedList<>();

        ConcurrentHashMap<Integer, Object> concurrentHashMap = new ConcurrentHashMap<>();

    }

}
